AK47s vs. bean bags in border drug wars

For the past few weeks, CBS News has been reporting on a controversial operation by the ATF that may have helped put lethal weapons in the hands of Mexican gangs. CBS News investigative correspondent Sharyl Attkisson reports some of those weapons have been implicated in the death of a U.S. Border patrol agent.

While ATF was allegedly allowing Mexican drug cartels to be armed with assault rifles from the U.S., a special Border Patrol team in Arizona was fighting, in part, with bean bag guns the night of Dec. 14, 2010.

That's according to newly-released court documents relating to the murder of Border Patrol Agent Brian Terry. Bean bag guns are often part of standard issue weapons so agents can choose non-lethal force.

The documents say Terry's squad spotted a group of illegal immigrants, some with assault rifles. When they refused to drop their weapons, agents fired "less than lethal" bean bags. The bandits fired back with real bullets.

Terry was shot and killed. His partners returned fire with a rifle and pistol, but it was too late.

The bandits' rifles trace back to a controversial ATF program called "Fast and Furious." ATF Agent John Dodson and others told CBS News they were assigned to watch as those exact rifles and thousands more guns were sold to suspected gunrunners and let out on the street -- to try build a big case. It's called letting guns "walk." The Department of Justice and ATF officials deny it.

"I've been doing it every day since I got here," agent Dodson said.

Attkisson asked, "Do you feel like there was a cover-up, or is there a cover-up attempt being made on some level?"

"Yes ma'am," he replied. "I mean ultimately, doesn't there have to be?"

Today, Terry's sister, Kelly Willis, reacted to Dodson's speaking out to CBS News. Willis said her family members were calling each other, in tears, after he came forward. "That somebody would put their job on the line like that for my family to give us the information that we need," Willis said.

Officials say three illegal immigrants arrested when Terry was gunned down could not be connected to the crime and were returned to Mexico. A fourth person is being held, but isn't charged in the murder.